The present invention relates to parallel comparators and more particularly to binary MOS parallel comparators.
In a book by A. Shah et al, "Integrierte Schaltungen in digitalen Systemen," Vol. 2, Basel, 1977, pages 129 to 143, various types of parallel comparators are described. Two of these types are the ripple-carry parallel comparator, explained on page 136 of that book, and the carry-lookahead parallel comparator, described on pages 140 and 141. The information given in this book is based on commercially available bipolar integrated circuits, and the parallel comparators are described with the aid of block diagrams in which the basic logic gates are used, i.e., AND, OR, NAND, NOR, equivalence (EXCLUSIVE-NOR) and EXCLUSIVE-OR gates, and inverter stages.
Direct application of the fundamental principles of conventional parallel comparators, explained with reference to the aforementioned bipolar integrated circuits, to integrated circuits using insulated-gate field-effect transistors, i.e., to so-called MOS circuits, is not readily possible because MOS technology and bipolar technology differ widely in some respects.